1. Field of the Technology
The present technology relates to a toner and a method for manufacturing the same.
2. Description of the Related Art
Toners for visualizing latent images are used in various image forming processes and for example, are used in an electrophotographic image forming process.
Image forming apparatuses employing the electrophotographic image forming process generally execute a charging step of uniformly charging a photosensitive layer on the surface of a photoreceptor drum serving as a latent image bearing member, an exposure step of projecting signal light of an original image on the surface of the photoreceptor drum that is being charged to form an electrostatic latent image, a development step of visualizing the electrostatic latent image on the surface of the photoreceptor drum by supplying an electrophotographic toner thereto, a transfer step of transferring a toner image on the surface of the photoreceptor drum to a recording medium such as paper and OHP sheets, a fixing step of fixing the toner image onto the recording medium under heat, pressure and the like, and a cleaning step of eliminating the toner and the like remaining on the surface of the photoreceptor drum after the toner image is transferred, with a cleaning blade for cleaning, to form a desired image on the recording medium. Transfer of a toner image to a recording medium may be performed through an intermediate transfer medium.
The electrophotographic toner for use in such image formation is manufactured, for example, by a knead-pulverization method, a polymerization method represented by a suspension polymerization method, an emulsification polymerization method and the like. Among them, in the knead-pulverization method, the toner is manufactured in such a manner that toner materials including a binder resin and a colorant as main components, to which a release agent, a charge control agent and the like are added as necessary and mixed, are melt-kneaded, cooled and solidified, then subjected to pulverization and classification.
In recent years, numerous efforts have been made in various technical fields from a viewpoint of global environmental protection. Today, oil is used as materials of many products, and energy is necessary for manufacturing and burning such materials, and carbon dioxide is generated. Efforts for reducing such energy and carbon dioxide are very important as global warming countermeasures.
For new efforts for reducing carbon dioxide as global warming countermeasures, much attention has been focused on the use of a plant-derived resource called biomass. Because the carbon dioxide generated in burning the biomass originates from the carbon dioxide which was present in the atmosphere and was taken in a plant through photosynthesis, the whole balance of input and output amounts of the carbon dioxide in the atmosphere is zero. In this manner, the property which does not affect an increase and a decrease in the carbon dioxide in the atmosphere is called carbon-neutral, and the use of the biomass having the carbon-neutral property is not considered to increase the amount of the carbon dioxide in the atmosphere. The biomass material made from such biomass is called by terms, such as a biomass polymer, a biomass plastic, or an oil-free polymer material, and the material of such biomass material is a monomer called a biomass monomer.
Also in the electrophotographic field there have been made many efforts to use the biomass which is a resource excellent in environmental safety and effective for suppressing increase in the carbon dioxide.
In addition, Japanese Unexamined Patent Publication JP-A 2008-122509 discloses a resin composition for an electrophotographic toner which contains a polyester resin having a softening temperature of 80 to 120° C. which is obtained from rosin as an essential component, and a polyester resin having a softening temperature of 160° C. or higher which is obtained from a polyepoxy compound as an essential component, and has low-temperature fixability, hot-offset resistance and development durability.
However, in the toner manufactured by the method disclosed in JP-A 2008-122509, when a rosin content in the resin composition is increased in order to enhance utilization rate of biomass, the toner becomes fragile. When such a toner is used as a developer, stress due to agitating in a development tank or the like causes a problem that the toner is crushed and fine powder is generated so that the charge amount is not stabilized, and that elasticity of the toner is decreased and hot offset easily occurs.